The present invention is directed to a high frequency (HF) direction finder for automobiles.
A prior art direction finder is disclosed in European Patent Application No. 0,363,619. It is not possible for the antennas of this prior art direction finder to be mounted in the immediate vicinity of the surface structure of the vehicle so as to be completely concealed. When the antennas are mounted near the surface, the signal to noise ratio (S/N) at the output of the antennas becomes too low to obtain a perfect bearing. Therefore, the antennas of the prior art direction finder must be mounted more or less visibly in areas which are free from the metal body of the vehicle. For example, in U.S. Pat. No. 4,003,057 thin antenna wires are stretched across the rear window of the vehicle for use as antennas. However, this does not make the antenna completely invisible. An automotive vehicle equipped with such a HF direction finder is not optimally suited for tracking and observing objects or vehicles marked with a target transmitter, because by using these antennas a tracked person will readily recognize that he is being followed by a vehicle.